Backup singers come to the fore

You may not know their faces - and in many instances, you could not SEE their faces - but their voices have graced some of the most memorable pop songs ever recorded. Background vocalists have been an integral part of music, but the backup singers giving their support to headline acts have usually been unsung, until now.

A new documentary, "Twenty Feet From Stardom," which debuted at the Sundance Film Festival and is now entering theatrical release, shines a light on singers who have often sung in the shadows.

By CBSNews.com senior producer David Morgan

Credit: Radius

Morgan Neville, director of "Twenty Feet From Stardom" (left, with singer Darlene Love), told correspondent Ben Tracy, "I don't think [background singers] get enough credit, because they don't get any credit. People think being a backup singer is about singing ooooh or ahhhhhh. But it's about so much more -- the way they sing, the way they do harmony.

"They're just incredible musicians. They're the most incredible artists you've never heard of."

Credit: Radius

In 1966 Merry Clayton was hired by Ray Charles as one of his Raelettes (seen here on the far left of the quartet).

"I had no problem with being a background singer, a sideground singer, an under-the-ground singer," Clayton told correspondent Ben Tracy. "I was just a singer who happened to sing background."

She went on to sing background for some of the biggest names in music, including Joe Cocker, Neil Diamond, Barbra Streisand, Carole King, The Doors, Lynyrd Skynyrd, and The Rolling Stones, giving an iconic performance in "Gimme Shelter."

Credit: Radius

Record producer Lou Adler and singer Merry Clayton.

Like many backup singers, Clayton pursued a solo career, and released several albums in the '70s, but none launched her to the status of public recognition shared by the singers for whom she did background vocals.

"You have all these people telling you how amazing you are; was it ever disappointing that it didn't get bigger by yourself as a solo artist?" Tracy asked Clayton.

A new compilation album, "The Best of Merry Clayton," features selections from all three of her Ode albums.

Credit: Legacy Recordings

Darlene Love joined the Blossoms, a leading session group that, beginning in the late 1950s, had performed background vocals for such artists as Sam Cooke, Tom Jones, Frank Sinatra and Dionne Warwick.

Love also recorded for Phil Spector - and found her voice being released under other groups' names, such as The Crystals' 1962 hit, "He's a Rebel."

Credit: Radius

After a career break, Love returned to music, as both a solo artist and a backup singer for U2 and Cher. She also acted in the "Lethal Weapon" movies, and on stage in "Hairspray."

In 2011 Love was inducted into the Rock and Roll Hall of Fame.

Left: Singer Darlene Love, featured in the documentary "Twenty Feet From Stardom."

Credit: Radius

Judith Hill (far right) says singing background is a good life, but it's not entirely charmed. Despite having performed regularly with such big-name acts as Stevie Wonder, Elton John and Michael Jackson, until recently she had to live with her parents in order to pay her bills.

Credit: Radius

Hill was picked by Michael Jackson to sing with him on his "This Is It" world tour, which was canceled by Jackson's untimely death.

"Where do you find the confidence to go face-to-face with Michael Jackson?" asked Ben Tracy.

"You don't find the confidence; confidence was definitely not in the moment," Hill replied. "I think there was hysteria and nerves and craziness. My heart is racing and I'm like, Oh my God, Michael Jackson is right here."

Credit: Radius

Judith Hill is pursuing a solo career, and recently competed on the TV competition, "The Voice."

Credit: Radius

Lisa Fischer (left, in "Twenty Feet from Stardom") has sung background for Sting and has toured with The Rolling Stones since 1989. In 1991 she released a solo recording, "So Intense"; a single from that album, "How Can I Ease the Pain," won her a Grammy Award.

Credit: Radius

A multi-exposure shot depicting a quartet of singer Lisa Fisher.

Despite her fame within the community of musicians, Fischer has not sought the kind of stardom of a platinum solo career. "Some people will do anything to be famous; other people just want to sing," she said.